Dynamo-electric machine.



PATENTED FEB. 25, 1908.

' 1904' 2 SHEETS-$11551 1.

H. GHITTY.

v DYNAMO ELECTRIC MACHINE APPLIUATION FILED JUNE 2 PATBNTED FEB. 25, 1908.

H. OHITTY. I DYNAMO ELECTRIC MACHINE PPLIOATION FILED JUNE 2; 1 04. A 9 2 SHEETS-SHEET 2.

, IYTTORNt'Y.

UNITED STATES PATENT QFFICE.

HENRY CHITTY, OF STRAND, LONDONQENGLAND.

DYNAMIC-ELECTRIC Specification of Letters Patent.

' Patented Feb. 25, 1908.

Application filed June 2. 1904. Serial No, 210i766.

To all whom it may concern:

' Be it known that I, HENRY CHIrrY, a subject of the King of Great Britain, residing at 2 Norfolk street, Strand, London, England, have inventeda new anduseful Improvemen-tin Dynamo-Electric Machines, of which the-followin is a s eciiication. I

a P ihis invention relates to electricmachlnes generally, such as generators, motors, rotary 1.0

transformers and the like, and has for its object to provide improved means for controlling the distribution of the magnetic-flux in. the s aceembraced between the leading and trai ing horns of adjacent pole pieces, so as to secure afixed position for the brushes and sparkless commutation over a much greater range of loads than has hitherto been possible. V

'll'ithfihis object in view, according to the present invention, abridge piece of magnetic material is provided, extending between ad j acent pol-e tips furnishinga shunt path for the magnetic flux. Bythis means, a strong magnetizing force maybe concentrated upon v a portion of the magnetic circuit at or near the leading horn, so that at no load this por-, tion will be so highlysaturated as to be practically incapable of any substantial increase in saturation. Hence, any ,additional'mag- 30' note motive forces coming into pla at full load, whether due to the shunt or the series windings on thepoles," or to the cross magnetizing effect of the current-flowing in the armature conductors, will not appreciably increase the magnetic flux-at this point.

For exam le, in a-machine with the well known'ra 'al type multipolar field magnet designed .to operate as a direct current generator withp'redetermined direction of rota,

tion, I construct the field ma et' with a bridge extending-from the-lea ing horn of one pole to the trailing horn. of the next, thus formingaclosed magnetic shunt circuit, in

which 18 "included acontracted neck form'ed in theleading side of the pole. Upon this neck, which is also in the circuit of-the effect 1 manner as, for example, by piercing the pole,

be concentrated.

ive flux, at the leadinglhorn, the combined magnetizing forcesoft e windings upon the two poles, actingin the.closed"circuit, may

' The neck maybeformed in any convenie'nt in a direction transverse to the line ofirotation with asuitablysha ped hole extending to within a very short distance of the pole face. Such proportions in regard to length.

and cross section may be given to this neck,

that, although a stronger magneto motive force will be acting in it than, in any other portion. of the magnetic circuit, raising it to a very high degree of saturation, the actual amount of fiiix need not be great. The bridge is made preferably of .a material having good magnetic permeability ;-it-should have substantial cross-section towards the: end where itjoins the trailing horn, and

the ratio between the effective and non effective lines of force in the contractedneck may be regulated by varying the cross-section of the bridge-piece towards the end join ing the leading horn. By regulating the cross-section of the bridge near the leading horn, the non-effective lines of force may be limited to a comparatively small of the effective flux per pole, and 0 density under theleading horn kept lower than elsewhere throughout the air gap. The bridge ercentage t piece is preferably. pierced by ventilation increased, will sprea out along the bridge, taking advantage of the easier path to the armature Icore offered through teeth less saturated than those immediately under the pole'face. It will thus be seen that by the means herein described the flux on the trailin side of the pole maybe made toincrease and advance towards the neutral point with in crease of load,;while on the leading side it.

may be'inade to have a lower value and be kept approximately constant at all loads. Moreover, having a comparatively easy passage'through'the teeth, owing to the lower density, the flux will go straight to the armalture core, instead'ofspreading, as is usually the case. The neutra point, and with it the line of commutation, is consequently shifted back at no load, remaining fixed, enabling'a .tric machine.

T AVAILABLE COW backward lead to be'given' to the brushes, In the case of an electric motor, the lead would be.lorward,instead or" backward.

The invention is illustrated by way of example in the accompanying drawings in which Figure 1 is a diagrammatic representation of a dynamo electric machine in which the direction of rotation is constant with my invention. applied thereto. Fig. 2 is a diagram showing the distribution of the magnetic flux of such an electric machine. Fig. 3 is a view, showing one form of bridge piece in position between the poles ota dynamo elec- Fig. i is a plan of the bridge piece shown in Fig. 3, looking in an upward direction, and showing the ventilating passages provided therein. Fig. 5 is a section on the line VI.-VI. of Fig. l.

For convenience of description, that horn ,or tip of the pole piece under which, in accordance with the direction of rotation, any given armature conductor last passes as it leaves the poleis herein referred to as the leading horn, and the other as the trailing horn or ti 2..

Referring to Fig. 1, the pole'pieces of the machine are indicated at 1, and the yokev connecting them at 2. The bridge piece extending between the pole tips is shown at 3, and a contracted neck i is here shown. as being formed. in the leading side of the pole piece, by means of a hole or orifice extend ing partly or entirely through the pole piece tip bf the pole piece in a direction transverse to the direction of rotation. This contracted neck may be formed many convenient manner for 111- a stance by a slot which may be left open or,

desired, filled with some non-magnetie material as conventionally indicated in the slots at the right hand side of Fig. 1. T he armature core is indicated at 6, and shown here as being provided with teeth 7, the' direction of rotation of the armature being indicated by the arrow. The distribution of the magnetic flux while the machine is in operation is diagrammatically represented by the dotted lines in 2, the lines of force here represented being t so of a generator.

A convenient re m. which the bridge piece m. y take, as applied to a machine in. wl'iieh the direction of rotation is c "ant. is illustr s. it th sides 8 the shape e bridge piece substantially symmetrical, while the e iective cross see is reduced for the greater portion of length towards that end 9 nextthe leading lrown in Fig. 5. Ventilating passages 10 are provided in the body of the bridge piece, and the reduction in cross section may also be effected by maks to increase in ding tip of theof these means e ventilating passa Tne approach Either or iece.

can

seaoii section, or any other suitable means which will effect the same purpose. The bridge piece may be maintained in position by means of dowel pins or screws 13 located at the junction of the bridge and pole pieces.

The bridge piece may also, if desired, be

utilized to support the field coils 12 of the machine. For this purpose a plate 14 is located on the field coil and a screw 11 projecting from a lug in the bridge piece is adapted to abut against this plate. By adjusting the screw 11 the desired amount of pressure may be brought to bear on the field coil 12.

it will be obvious that the bridge piece may be formed in'one with the pole pieces, if desired, and other modifications as to shape and construction both of the'pole and bridge pieces may be made without departing from the spirit and scope of the invention. The invention is also not dependent upon there being windings on the poles, as an electric machine constructed in accordance with this invention is capable of operating satisfactorily as a'motor Withoutany field magnet windings whatever, the armature exciting its own field.-

I claim as my invention:

i. in a dynamo electric machine having projecting pole pieces the combination with a pole piece having a portion in a direction transverse to that of rotation ofthe armature removedthereirom, of a bridge piece of magnetic material extending between adjacent pole pieces and forming a shunt path for/the magnetic flux. I

2. in a dynamo electric machine having radial pole pieces the combination with a, pole piece having a portion near the polar face in a direction transverse to that of rotation of the revolving member of the machine removed therefrom, of a bridge piece of magnetic material extending between the tips of adjacent pole pieces and forming a shunt path for the magnetic thug.

3. in a dynamo electric; machine having radial pole pieces the combination with a pole piece pierced with a hole in a direction transverse'to that of rotationof the revolving member of the machine, of a bridge piece of magnetic material extending between adjaunt pole pieces and forming a shunt path. flux.

inamo electric machine having in a direction transverse to that of rotation of a pole piece having its tip pierced with a hole.

- tion of the revolving member of the machine,

of a bridge piece of magnetic material extending between the tips of adjacentpole pieces and forming a shunt path for the magnetic flux.

7. Ina dynamo electric machine having projecting pole pieces the combination with a pole piece having a portion-near the leading tip in a direction transverse to that of rotation. of the revolving member of the machine removed therefrom thereby "forming a contracted neck in the pole piece, of a bridge piece of magnetic material extending between adjacent pole pieces and forming a radial pole pieces the combination with a shunt path for the magnetic flux.

8.- In a dynamo electric machine having pole piece having portion near the leading up in a direct-ion transverse to that or rotatlon of the revolving member of the machine removed therefrom thereby forming a contracted neck in the pole iece, of a bridge p'iece of magnetic materia ext-ending .be-

tween the tips of adjacent pole pieces and forming a; shunt path for the magnetic flux.

5%. In a dynamo electric machine having projecting'pole pieces the combination with a polepiece having a pnrtion of its substance in a direction transverse to that of rotation of the revolving member of the machine and located near the polar face removed therefrom, of a bridge piece of varyin cross section formed of magnetic material extending between ad acent pole pieces and forming ashunt athior the magnetic flux.

10. n a dynamo electric machine having projecting pole pieces the combination with a pole piece pierced with a hole in a direction transverse to that of rotation of the revolving member of. the machine and located near the face of the pole piece, of a bridge piece of varying cross section formed of magnetic material extending between adjacent pole pieces and forming a shunt path for the magnetic flux. 1

11. In a dynamo electric machine having projecting pole pieces the combination with a pole piece having a portion in a direction transverse to that of rotation of the revolving member of the machine removed there from, of a bridge piece of varying cross sec tion formed of magnetic material located atthe extremities of adjacent pole pieces andforming a shunt path for the magnetic flux 12. In a dynamo electric machinehaving radial pole pieces the combination with: a

.- pole pierced with a hole in adirection train;-

13. In a dynamo electric machine having projecting pole pieces the combination with a pole piece having a portion in a direction transverse to thatot rotation of the revolving member of the machin'eremoved therefrom, of a bridge piece of magnetic material extending between adjacent pole pieces and forming a shunt path for the magnetic flux and having a greater cross section at its end which is adjacent tov the trailing pole piece than at that adjoining the leading pole piece,

14:. In a dynamo electric machine having projecting pole pieces the combination with a pole piece having a portion in direction. transverse to that of rotation of the revolving member of the machine removed therefrom, of a bridge piece of magnetic material located at the extremities of adjacent pole pieces forming a shunt path for the magnetic flux and having a greater cross section at its end which is adjacentito the trailing pole piece than at that adjoining the leading pole piece.

15. In a dynamo electric machine having projecting pole pieces the combination with a pole piece pierced with a hole in a direction transverse to that of rotationof the revolving member of the machine, of a bridge piece of magnetic material extending between the tips of adjacent pole pieces and forming a shunt path for the magnetic flux, said bridge piece being provided with ventilation chan-' nels, -c

16. In a dynamo electric machine having radial pole pieces the combination with a pole piece having a portion near the leading tip removed. therefrom in a direction transverseto that of rotation ot the revolving member of the machine thereby forming a contracted neck in the pole piece, of a bridge piece of magnetic material extending between adjacent pole pieces and forming a shuntpath for the magnetic flux, said bridge piece being provided with ventilation ducts.

17. In a dynamo electric machine having projecting pole pieces the combination with a'pole piece having a portion in a direction transverse to that of rotation of the revolving member of the machine removed therefrom,

of a bridge piece of magnetic material ex-' tending between adjacent pole pieces and forming a shunt path for .the magnetic flux, said bridge piece being provided with ventilation ducts in the form of slots extending in a direction from one pole pieceto the next.

- 18. In a dynamo electric machine having projecting pole pieces the combination with a pole p1ece pierced with a hole in a direction transverse to that of rotation of the revolving member of the machine and located near the face of the pole piece, of a bridge piece of magnetic material extending between the extip removed therefrom in a directiontrans verse to that of rotation of the revolving member of the machine thereby forming a contracted neck in the pole piece, of a bridge piece of magnetic material extending between adjacent pole pieces and forming a shunt path for the magnetic flux, said bridge piece being provided with ventilation ducts in the form of slots extending in a direction from one pole piece to the next.

20. In a dynamo electric machine having projecting pole pieces the combination with a pole piece having a portion removed in a direction transverse to that of. rotation of the revolving member of the machine, of a bridge piece of magnetic material extending betweenjadjacent pole pieces and forming a shunt path for the magnetic flux, said bridge piece'being provided with ventilation channe'ls in' the form of slots extending in a dime-- tionfrom one pole piece to the next the cross sc'tioriof saidslots increasing from the trailing the leading pole tip.

421 I-n a dynamo electric machine having proj eating pole piecesthe combination with a pole piece having a hole piercing it in a direction transverse to that of rotation of the revolving n1ember of the machine and located near the polar'face, of a bridge piece of magnetic material extending between the tips of adjacent pole. pieces and forming a shunt path piece, of a bridge piece of magnetic material in a direction from one pole piece to the next the cross section of said slots increasing from the trailing to the leading pole tip.

23. In a dynamo electric machine having projecting pole pieces the combination with a pole piece having portions in a direction transverse to that o rotation of the revolving member of the machine removed therefrom, of a bridge piece of magnetic material having its cross section greater at that end. adjacent to the trailing pole tip than at that end adjoining the leading pole tip, said bridge iece extending between adjacent pole pieces forming a shunt path for the magnetic flux and being provided with ventilation ducts in the form of slots extending in a direction from one pole piece to the next the cross section of said slots increasing from the trailing to the leading pole tip.

24. In a dynamo electric machine having radial pole pieces the combination with a pole piece pierced with a' hole in a direction transverse to that of rotation of the revolvin member of the machine, of a bridge piece 0 magnetic material having its cross section greater at that end adjacent to the trailing pole ti than at that end adjoining the leadpiece to the next the cross section of said slots increasing from'thetrailing to the lead- 7 ing pole tip.

25. Ina dynamo electric machine having projecting pole pieces the combination with a pole piece having a portion removed near the leading tip in a direction transverse to that of rotationjof the revolving member of the machine and forming a contracted neck in the pole 1piece, of. a bridge piece of magnetic materia end adjacent to the trailing pole top than at that end adjoining the leading pole tip said bridge iece extending between adjacent pole pieces orming a shunt path for the ma netic flux, and being provided with ventilation ducts in the form of slots extending in a direction from one pole piece to the next the cross section of said slots increasing from-the trailing to the leading pole tip.

26'. In a dynamo electric machine having projecting ole pieces the combination with a pole piece aving'a portion removed in a direction transverse to that'of rotation of the revolving member of the machine, of a bridge piece of magnetic material extending behaving its cross section greater at that tween adjacent pole pieces and forming ashunt path for the magnetic flux, and means for holding the coil surrounding the pole two subscribing witnesses this 16th piece in 'positign coigiplglising a screw adapged May 1904. to en a 'e Wit the ri e iece and to a ut T 7 r1 again st e plate placed 011 @11 3, Winding around BERRY bHITTY' 5 the pole piece. Witnesses In testimony whereof I have signed my I A. A. BERGNI, name to this specification in the presence of I W. I. SKERTEN.

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